Transformation of functional groups and environmentally persistent free radicals in hydrothermal carbonisation of lignin

Xiuxiu Ruan, Yaoyu Liu, Guoqing Wang, Ray L. Frost, Guangren Qian, Daniel C.W. Tsang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

30 Citations (Scopus)


In this study, lignin was selected as the main component of waste biomass to synthesise carbonaceous adsorbents with environmentally persistent free radicals (EPFRs) through hydrothermal carbonisation (HTC) under different conditions. The HTC method with Fe(III) doping was superior for promoting dehydration and decarboxylation of lignin hydrochar than that with HTC Cu(II) doping. The deconstruction of oxygen-containing groups of lignin was reduced while esterification was enhanced by Fe(III). The Fe(III) addition was conducive to the formation of EPFRs as carbon-centred radicals with an adjacent oxygen atom and oxygen-centred radicals. A comparison of lignin with cellulose and D-xylose suggests that the formed EPFRs on lignin hydrochar were derived from their phenolic hydroxyl groups. A high removal efficiency of bisphenol A by lignin hydrochar was observed owing to oxygen-centred radicals, which activated H 2 O 2 to produce [rad]OH. These results will facilitate the design and application of novel hydrochar materials with EPFRs.

Original languageEnglish
Pages (from-to)223-229
Number of pages7
JournalBioresource Technology
Publication statusPublished - Dec 2018


  • Biomass valorisation
  • Carbon-/oxygen-centred radicals
  • Fenton-like reaction
  • Hydrochar
  • Surface chemistry

ASJC Scopus subject areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal

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